Cardiac Sarcoidosis

Cardiac Sarcoidosis: Sorting Fact from Fiction in This Rare Cardiomyopathy

Authors: Rajapreyar, Indranee; Langlois, Elizabeth

Sarcoidosis is a rare condition of granulomatous infiltration of many tissues of the body, including the heart. Cardiac sarcoidosis has been challenging to study, as it is often asymptomatic, although the initial presentation can be sudden cardiac death. The incidence and prevalence rates have been difficult to establish and no expert agreed upon guidelines for diagnosis and management of cardiac sarcoidosis exist, and clinical manifestations are varied. The pathophysiology of granuloma formation in the myocardium as well as other tissues is governed by immune response to some environmental antigen. Genetics is also thought to play a role, although gene alterations have not been extensively studied, and no specific set of genetic mutations has been identified to aid in identification of individuals at risk of developing disease. Epigenetic factors likely play a significant role in modulation of gene expression with respect to immune response. There is no standardized screening tool for the identification of cardiac sarcoidosis. The presence of systemic sarcoidosis and new-onset third-degree heart block or ventricular arrhythmias warrants further investigation for cardiac sarcoidosis. MRI and PET are useful in helping to identify cardiac sarcoidosis but are not stand-alone tests. Endomyocardial biopsy is the gold standard but has a low yield owing to the patchy nature of granuloma formation in the myocardium. Therapy should be instituted early and involves immunosuppressive therapy with predominant use of corticosteroids. Arrhythmias, either ventricular or high-grade heart blocks, are managed with device therapy. Clinical presentation may warrant use of antiarrhythmic agents and/or catheter ablation. Survival and disease prognosis are dependent on early diagnosis and treatment. This review details the current understanding of cardiac sarcoidosis and highlights diagnostic strategies and treatment with the aim of guiding the clinician to early identification of patients and implementation of appropriate management in this rare disease entity.